All Java Files becomes red marked as error. but project build successfully

I am using android studio 1.0. I am developing a small android application. When i was editing the code in one of my java file in android studio, power cut happened. After power came, i open the android studio and open my project, all files in the java folder marked as red indicationg error. but the projects build successfully. when i sync with gradle. it also done successfully. and perfectly runs in the device after launced the app in my phone.. but the red mark not disappear even i close the project and reopen. If i create new project also, the same things happen again. i can't understand what's happened. i also tried re install my jdk 1.7
Can anyone help me, how to fix this bug. please give exact solution. i don't like suggestions like to re install android studio